There are several choices as shock absorbing material used for protecting products from damages due to physical shocks applied to the products from mishandling or stacking. One of those choices is styrofoam. Although using styrofoam as packaging material has benefits such as good thermal insulation and light weight, it also has various disadvantages. For example, recycling the styrofoam is not possible, soot is produced when it burns, a flake or chip comes off when it is snagged because of its brittleness, and expensive mold is needed for its production, and a relatively large warehouse is necessary for storage.
Therefore, to solve such problems noted above, other packing materials and methods have been proposed. One method is a fluid container that seals in liquid or gas such as air (hereinafter “air-packing device”). Such an air-packing device has excellent characteristics that solve the problems involved with the styrofoam. First, because the air-packing device is made only of thin plastic films, it does not need a large warehouse for storage until immediately prior to product packing when the air-packing device has to be inflated. Second, a large mold is not necessary for its production because of its simple structure. Third, the air-packing device does not produce a chip or dust which may have adverse effects on precision products. Furthermore, recyclable materials can be used for the films forming the air-packing device. Additionally, the air-packing device can be produced with low cost and transported with low cost.
An example of a structure of such an air-packing device is shown in FIG. 1. The air-packing device 20 includes a plurality of air containers 22 and check valves 24, a guide passage 21 and an air inlet 25. The air from the air inlet 25 is supplied to the air containers 22 through the air passage 21 and the check valves 24. The air-packing device 20 is composed of two thermoplastic films that are bonded together at bonding areas 23a. 
As shown, tach air container 22 is provided with a check valve 24. One of the purposes of having multiple air containers 22 with corresponding check valves 24 is to increase the reliability of the air-packing device. Because each air container 22 has its own check valve 24, it is independent from the others in terms of maintaining the air. Thus, even if one of the air containers suffer from an air leakage for some reason, the air-packing device 20 can still function as a shock absorber for packing the product using the remaining air containers 22 that are still intact and remain inflated.
FIG. 2 is a plan view of the air-packing device 20 of FIG. 1 when it is not inflated to show bonding areas for closing two thermoplastic films. The thermoplastic films of the air-packing device 20 are bonded (heat-sealed) together at bonding areas 23a which are rectangular periphery thereof to air-tightly close the edges of the air-packing device 20. The thermoplastic films of the air-packing device 20 are also bonded together at bonding areas 23b which form the boundaries of air containers 22 to air-tightly separate the air containers 22 from one another.
When using the air-packing device 20, each air container 22 is filled with air from the air inlet 25 through the guide passage 21 and the check valve 24. After filling the device with the air, the expansion of each air container 22 is maintained because each check-valve 24 prevents the reverse flow of the air. The check valve 24 is typically made of two rectangular thermoplastic valve films that are bonded together to form an air pipe. The air pipe has a tip opening and a valve body to allow the air flowing in the forward direction through the air pipe from the tip opening but to disallow the air to flow in the backward direction.
Air-packing devices are becoming more and more popular because of the advantages noted above. There is an increasing need to store and carry precision products or articles which are sensitive to shocks and impacts often involved in shipment of the products. There are many other types of product, such as wine bottles, DVD drivers, music instruments, glass or ceramic wares, antiques, etc. that need special attention so as not to receive a shock, vibration or other mechanical impact. Thus, it is desired that the air-packing device with a simple and low cost structure protects the product to minimize the shock and impact.